Track sprocket dimension and connection to motor shaft

[tim.ruban]

1) I can't seem to find the dimension of the inner diameter of the Lynxmotion Track Sprocket - 6 Tooth (Pair) SPRK-01 (Product code : RB-Lyn-168). How can I find it?

2) I'm not sure how I can connect this wheel to a motor shaft, but the stepper motor I'm using is the 12V 0.68A 125oz-in Unipolar Stepper Motor (Product code : RB-Soy-14). Any suggestions as to how to connect the track sprocket to the stepper motor mentioned above?

Thank you.

[Cbenson]

1) The bore diameter is about 3/8". You can download a CAD file of the wheel here.

2) There are a few hubs which are specific to this sprocket: 4mm and 6mm

RB-Soy-14 has a 6.35mm diameter shaft which means if you want to connect it to this sprocket, you'd need the version of the hub designed for a 6mm shaft and bore a slightly larger diameter hole using a tabletop drill press. Note that these sprockets are intended to be used with certain DC gear motors.

[tim.ruban]

Thanks a lot for the reply.

I'm guessing that when you say "if you want to connect it to this sprocket, you'd need the 6mm shaft" you actually mean the hub with a 6mm bore. But that makes sense. I have access to a vertical mill, so I'll be okay for drilling a slightly larger hole.

My project requires a preliminary CAD drawing assembly before I can go ahead and purchase all these materials. How do I go about obtaining the CAD files of the 6mm hub, the RB-Soy-14 stepper motor, the RB-Lyn-170 lynxmotion track, and the RB-Phi-67 motor controller?

[Cbenson]

Re-phrased. My bad.

Unfortunately there is not CAD version of the hub or the stepper motor. You can infer most of the dimensions of the hub from the CAD drawing of the sprocket, and can draw the stepper motor based on the 2D drawing (note L~76mm).

[tim.ruban]

My conveyor belt system will be exposed to temperatures to up to 100 degrees Celsius, whereas the Lynxmotion Track only handles up to 66C. Is there any other conveyor system that has adjustable length, that is at least 1" wide (preferably 2") and that handles higher temperatures? I can't seem to find any.

Thanks.

[Cbenson]

The products we offer are tracks for robots; if you need conveyor belting, you may want to search for that (metal would be a good temperature resistant option).

[tim.ruban]

When it comes more precisely to fixating a hub on the motor shaft - do I drill the 6mm hole to [6.35" MINUS 2-3 thousands of an inch] and then press-fit it on the shaft using a clamp? Won't that damage the motor? Do most people just use glue? I'm no longer using Lynxmotion. I'm gonna be using a simple piece of brass or another metal that's easy to press fit with.

[Cbenson]

Press fitting a hub certainly does have the potential to destroy the motor if the shaft moves within the motor. Most people use one of the following methods to secure a hub to a shaft:

• Set screw in the hub (if you are making one yourself, drill the bore diameter so the shafts easily fits inside, then drill and thread a hole perpendicular to the shaft where you will place a set screw which will them be pressed up against the shaft (ideally against the flat part of a D-shaped shaft).
• You can also use a clamping hub - this often is a hub with a slot cut out, and a screw at 90 degrees to pull the two ends together, thus "clamping" it to the shaft.
• Some hubs have a slot for a key (rectangular piece of metal) which must also correspond to a keyway in the shaft. Not all shafts have this option, but if they do, you are guaranteed not to have any slippage. You would also need two set screw collars (one on either side of the hub) to prevent it from moving.
• Press fit: ensure the shaft cannot move; press the rear of the shaft against a solid object before pressing a hub onto the "drive" end.